On July 23, the European Medicines Agency (EMA) Committee for Medicinal Products for Human Use (CHMP) recommended the rejection of Kyowa Kirin’s Nouryant (istradefylline) as adjunctive therapy for the treatment of Parkinson’s disease (PD).
This news came as a surprise to the PD community, as the same drug has been approved in the US and Japan since 2019 and 2013, respectively. With the EMA’s final decision on Nouryant’s approval for PD expected in October 2021, the CHMP’s opinion all but halts Nouryant’s launch plan in Europe, causing a serious setback for the once-promising, first-in-class drug.
Nouryant, which is also marketed as Nourianz in the US, is an adenosine A2 receptor inhibitor that is used as an add-on treatment for levodopa therapy in patients experiencing end-of-dose motor fluctuations.
The CHMP’s opinion cited that the efficacy data presented from eight Phase II and Phase III trials did not show consistent benefits with the drug, as four out of the eight trials failed to show any significant reduction in motor fluctuations experienced in PD patients, including two negative trials conducted in European populations. On the other hand, the US Food and Drug Administration (FDA) approval in 2019 was based on the positive results of four safety and efficacy trials that included a total of 1,143 patients.
Key opinion leaders (KOLs) interviewed by GlobalData had mixed views about Nouryant’s efficacy and safety as add-on therapy in PD patients. Some noted that they had seen faster effects with Nouryant reducing off-episodes compared to other therapeutic classes. However, some KOLs still had concerns regarding its unclear mechanism of action and neuropsychiatric side effects. GlobalData forecasts that Nouryant will generate peak sales of $200m in 2023 in the US and Japan, before being hit by the erosion of cheaper generics starting in 2024. As such, Nouryant is expected to only generate $57m in the US and Japan by 2029.
Effective treatment of motor fluctuations remains one of the key unmet needs in the PD market. Although levodopa is a highly effective drug, the emergence of motor fluctuations due to prolonged levodopa use is a major challenge for physicians and patients. Therefore, the market for new PD products aimed at controlling motor fluctuations holds great commercial potential. As such, GlobalData expects that the recent setback of the CHMP’s rejection is not likely to have a negative impact on Nouryant’s current uptake in the US and Japan, despite the fact that it is has delayed the drug’s expansion in Europe.